Taint
Taint emphasizes the loss of purity or cleanliness. It suggests something that was once good or innocent has been spoiled or corrupted, even by a small amount of contamination.
This can be literal, like tainted meat with bacteria, or metaphorical, like a reputation tainted by scandal.
Pollute
Pollute implies a more complete and severe contamination. It often refers to the introduction of harmful or poisonous substances that make something unfit for its original purpose. Think of polluted air filled with smog or a river polluted with industrial waste.
Analogy
If you dip a dirty finger in the water, it’s tainted. The water isn’t completely unusable, but it’s not as pure as it was before. If you pour a whole bottle of ink into the water, it’s polluted. The water is completely unusable for drinking.
Summary
In some cases, taint and pollute can be used interchangeably. To be more precise, “taint” suggests a lesser degree of contamination, while “pollute” implies a more significant and harmful effect.